duke@435: /*
duke@435:  * Copyright 1997-2007 Sun Microsystems, Inc.  All Rights Reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
duke@435:  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435:  * CA 95054 USA or visit www.sun.com if you need additional information or
duke@435:  * have any questions.
duke@435:  *
duke@435:  */
duke@435: 
duke@435: // A Generation models a heap area for similarly-aged objects.
duke@435: // It will contain one ore more spaces holding the actual objects.
duke@435: //
duke@435: // The Generation class hierarchy:
duke@435: //
duke@435: // Generation                      - abstract base class
duke@435: // - DefNewGeneration              - allocation area (copy collected)
duke@435: //   - ParNewGeneration            - a DefNewGeneration that is collected by
duke@435: //                                   several threads
duke@435: // - CardGeneration                 - abstract class adding offset array behavior
duke@435: //   - OneContigSpaceCardGeneration - abstract class holding a single
duke@435: //                                    contiguous space with card marking
duke@435: //     - TenuredGeneration         - tenured (old object) space (markSweepCompact)
duke@435: //     - CompactingPermGenGen      - reflective object area (klasses, methods, symbols, ...)
duke@435: //   - ConcurrentMarkSweepGeneration - Mostly Concurrent Mark Sweep Generation
duke@435: //                                       (Detlefs-Printezis refinement of
duke@435: //                                       Boehm-Demers-Schenker)
duke@435: //
duke@435: // The system configurations currently allowed are:
duke@435: //
duke@435: //   DefNewGeneration + TenuredGeneration + PermGeneration
duke@435: //   DefNewGeneration + ConcurrentMarkSweepGeneration + ConcurrentMarkSweepPermGen
duke@435: //
duke@435: //   ParNewGeneration + TenuredGeneration + PermGeneration
duke@435: //   ParNewGeneration + ConcurrentMarkSweepGeneration + ConcurrentMarkSweepPermGen
duke@435: //
duke@435: 
duke@435: class DefNewGeneration;
duke@435: class GenerationSpec;
duke@435: class CompactibleSpace;
duke@435: class ContiguousSpace;
duke@435: class CompactPoint;
duke@435: class OopsInGenClosure;
duke@435: class OopClosure;
duke@435: class ScanClosure;
duke@435: class FastScanClosure;
duke@435: class GenCollectedHeap;
duke@435: class GenRemSet;
duke@435: class GCStats;
duke@435: 
duke@435: // A "ScratchBlock" represents a block of memory in one generation usable by
duke@435: // another.  It represents "num_words" free words, starting at and including
duke@435: // the address of "this".
duke@435: struct ScratchBlock {
duke@435:   ScratchBlock* next;
duke@435:   size_t num_words;
duke@435:   HeapWord scratch_space[1];  // Actually, of size "num_words-2" (assuming
duke@435:                               // first two fields are word-sized.)
duke@435: };
duke@435: 
duke@435: 
duke@435: class Generation: public CHeapObj {
duke@435:   friend class VMStructs;
duke@435:  private:
duke@435:   jlong _time_of_last_gc; // time when last gc on this generation happened (ms)
duke@435:   MemRegion _prev_used_region; // for collectors that want to "remember" a value for
duke@435:                                // used region at some specific point during collection.
duke@435: 
duke@435:  protected:
duke@435:   // Minimum and maximum addresses for memory reserved (not necessarily
duke@435:   // committed) for generation.
duke@435:   // Used by card marking code. Must not overlap with address ranges of
duke@435:   // other generations.
duke@435:   MemRegion _reserved;
duke@435: 
duke@435:   // Memory area reserved for generation
duke@435:   VirtualSpace _virtual_space;
duke@435: 
duke@435:   // Level in the generation hierarchy.
duke@435:   int _level;
duke@435: 
duke@435:   // ("Weak") Reference processing support
duke@435:   ReferenceProcessor* _ref_processor;
duke@435: 
duke@435:   // Performance Counters
duke@435:   CollectorCounters* _gc_counters;
duke@435: 
duke@435:   // Statistics for garbage collection
duke@435:   GCStats* _gc_stats;
duke@435: 
duke@435:   // Returns the next generation in the configuration, or else NULL if this
duke@435:   // is the highest generation.
duke@435:   Generation* next_gen() const;
duke@435: 
duke@435:   // Initialize the generation.
duke@435:   Generation(ReservedSpace rs, size_t initial_byte_size, int level);
duke@435: 
duke@435:   // Apply "cl->do_oop" to (the address of) (exactly) all the ref fields in
duke@435:   // "sp" that point into younger generations.
duke@435:   // The iteration is only over objects allocated at the start of the
duke@435:   // iterations; objects allocated as a result of applying the closure are
duke@435:   // not included.
duke@435:   void younger_refs_in_space_iterate(Space* sp, OopsInGenClosure* cl);
duke@435: 
duke@435:  public:
duke@435:   // The set of possible generation kinds.
duke@435:   enum Name {
duke@435:     ASParNew,
duke@435:     ASConcurrentMarkSweep,
duke@435:     DefNew,
duke@435:     ParNew,
duke@435:     MarkSweepCompact,
duke@435:     ConcurrentMarkSweep,
duke@435:     Other
duke@435:   };
duke@435: 
duke@435:   enum SomePublicConstants {
duke@435:     // Generations are GenGrain-aligned and have size that are multiples of
duke@435:     // GenGrain.
duke@435:     LogOfGenGrain = 16,
duke@435:     GenGrain = 1 << LogOfGenGrain
duke@435:   };
duke@435: 
duke@435:   // allocate and initialize ("weak") refs processing support
duke@435:   virtual void ref_processor_init();
duke@435:   void set_ref_processor(ReferenceProcessor* rp) {
duke@435:     assert(_ref_processor == NULL, "clobbering existing _ref_processor");
duke@435:     _ref_processor = rp;
duke@435:   }
duke@435: 
duke@435:   virtual Generation::Name kind() { return Generation::Other; }
duke@435:   GenerationSpec* spec();
duke@435: 
duke@435:   // This properly belongs in the collector, but for now this
duke@435:   // will do.
duke@435:   virtual bool refs_discovery_is_atomic() const { return true;  }
duke@435:   virtual bool refs_discovery_is_mt()     const { return false; }
duke@435: 
duke@435:   // Space enquiries (results in bytes)
duke@435:   virtual size_t capacity() const = 0;  // The maximum number of object bytes the
duke@435:                                         // generation can currently hold.
duke@435:   virtual size_t used() const = 0;      // The number of used bytes in the gen.
duke@435:   virtual size_t free() const = 0;      // The number of free bytes in the gen.
duke@435: 
duke@435:   // Support for java.lang.Runtime.maxMemory(); see CollectedHeap.
duke@435:   // Returns the total number of bytes  available in a generation
duke@435:   // for the allocation of objects.
duke@435:   virtual size_t max_capacity() const;
duke@435: 
duke@435:   // If this is a young generation, the maximum number of bytes that can be
duke@435:   // allocated in this generation before a GC is triggered.
duke@435:   virtual size_t capacity_before_gc() const { return 0; }
duke@435: 
duke@435:   // The largest number of contiguous free bytes in the generation,
duke@435:   // including expansion  (Assumes called at a safepoint.)
duke@435:   virtual size_t contiguous_available() const = 0;
duke@435:   // The largest number of contiguous free bytes in this or any higher generation.
duke@435:   virtual size_t max_contiguous_available() const;
duke@435: 
duke@435:   // Returns true if promotions of the specified amount can
duke@435:   // be attempted safely (without a vm failure).
duke@435:   // Promotion of the full amount is not guaranteed but
duke@435:   // can be attempted.
duke@435:   //   younger_handles_promotion_failure
duke@435:   // is true if the younger generation handles a promotion
duke@435:   // failure.
duke@435:   virtual bool promotion_attempt_is_safe(size_t promotion_in_bytes,
duke@435:     bool younger_handles_promotion_failure) const;
duke@435: 
duke@435:   // Return an estimate of the maximum allocation that could be performed
duke@435:   // in the generation without triggering any collection or expansion
duke@435:   // activity.  It is "unsafe" because no locks are taken; the result
duke@435:   // should be treated as an approximation, not a guarantee, for use in
duke@435:   // heuristic resizing decisions.
duke@435:   virtual size_t unsafe_max_alloc_nogc() const = 0;
duke@435: 
duke@435:   // Returns true if this generation cannot be expanded further
duke@435:   // without a GC. Override as appropriate.
duke@435:   virtual bool is_maximal_no_gc() const {
duke@435:     return _virtual_space.uncommitted_size() == 0;
duke@435:   }
duke@435: 
duke@435:   MemRegion reserved() const { return _reserved; }
duke@435: 
duke@435:   // Returns a region guaranteed to contain all the objects in the
duke@435:   // generation.
duke@435:   virtual MemRegion used_region() const { return _reserved; }
duke@435: 
duke@435:   MemRegion prev_used_region() const { return _prev_used_region; }
duke@435:   virtual void  save_used_region()   { _prev_used_region = used_region(); }
duke@435: 
duke@435:   // Returns "TRUE" iff "p" points into an allocated object in the generation.
duke@435:   // For some kinds of generations, this may be an expensive operation.
duke@435:   // To avoid performance problems stemming from its inadvertent use in
duke@435:   // product jvm's, we restrict its use to assertion checking or
duke@435:   // verification only.
duke@435:   virtual bool is_in(const void* p) const;
duke@435: 
duke@435:   /* Returns "TRUE" iff "p" points into the reserved area of the generation. */
duke@435:   bool is_in_reserved(const void* p) const {
duke@435:     return _reserved.contains(p);
duke@435:   }
duke@435: 
duke@435:   // Check that the generation kind is DefNewGeneration or a sub
duke@435:   // class of DefNewGeneration and return a DefNewGeneration*
duke@435:   DefNewGeneration*  as_DefNewGeneration();
duke@435: 
duke@435:   // If some space in the generation contains the given "addr", return a
duke@435:   // pointer to that space, else return "NULL".
duke@435:   virtual Space* space_containing(const void* addr) const;
duke@435: 
duke@435:   // Iteration - do not use for time critical operations
duke@435:   virtual void space_iterate(SpaceClosure* blk, bool usedOnly = false) = 0;
duke@435: 
duke@435:   // Returns the first space, if any, in the generation that can participate
duke@435:   // in compaction, or else "NULL".
duke@435:   virtual CompactibleSpace* first_compaction_space() const = 0;
duke@435: 
duke@435:   // Returns "true" iff this generation should be used to allocate an
duke@435:   // object of the given size.  Young generations might
duke@435:   // wish to exclude very large objects, for example, since, if allocated
duke@435:   // often, they would greatly increase the frequency of young-gen
duke@435:   // collection.
duke@435:   virtual bool should_allocate(size_t word_size, bool is_tlab) {
duke@435:     bool result = false;
duke@435:     size_t overflow_limit = (size_t)1 << (BitsPerSize_t - LogHeapWordSize);
duke@435:     if (!is_tlab || supports_tlab_allocation()) {
duke@435:       result = (word_size > 0) && (word_size < overflow_limit);
duke@435:     }
duke@435:     return result;
duke@435:   }
duke@435: 
duke@435:   // Allocate and returns a block of the requested size, or returns "NULL".
duke@435:   // Assumes the caller has done any necessary locking.
duke@435:   virtual HeapWord* allocate(size_t word_size, bool is_tlab) = 0;
duke@435: 
duke@435:   // Like "allocate", but performs any necessary locking internally.
duke@435:   virtual HeapWord* par_allocate(size_t word_size, bool is_tlab) = 0;
duke@435: 
duke@435:   // A 'younger' gen has reached an allocation limit, and uses this to notify
duke@435:   // the next older gen.  The return value is a new limit, or NULL if none.  The
duke@435:   // caller must do the necessary locking.
duke@435:   virtual HeapWord* allocation_limit_reached(Space* space, HeapWord* top,
duke@435:                                              size_t word_size) {
duke@435:     return NULL;
duke@435:   }
duke@435: 
duke@435:   // Some generation may offer a region for shared, contiguous allocation,
duke@435:   // via inlined code (by exporting the address of the top and end fields
duke@435:   // defining the extent of the contiguous allocation region.)
duke@435: 
duke@435:   // This function returns "true" iff the heap supports this kind of
duke@435:   // allocation.  (More precisely, this means the style of allocation that
duke@435:   // increments *top_addr()" with a CAS.) (Default is "no".)
duke@435:   // A generation that supports this allocation style must use lock-free
duke@435:   // allocation for *all* allocation, since there are times when lock free
duke@435:   // allocation will be concurrent with plain "allocate" calls.
duke@435:   virtual bool supports_inline_contig_alloc() const { return false; }
duke@435: 
duke@435:   // These functions return the addresses of the fields that define the
duke@435:   // boundaries of the contiguous allocation area.  (These fields should be
duke@435:   // physicall near to one another.)
duke@435:   virtual HeapWord** top_addr() const { return NULL; }
duke@435:   virtual HeapWord** end_addr() const { return NULL; }
duke@435: 
duke@435:   // Thread-local allocation buffers
duke@435:   virtual bool supports_tlab_allocation() const { return false; }
duke@435:   virtual size_t tlab_capacity() const {
duke@435:     guarantee(false, "Generation doesn't support thread local allocation buffers");
duke@435:     return 0;
duke@435:   }
duke@435:   virtual size_t unsafe_max_tlab_alloc() const {
duke@435:     guarantee(false, "Generation doesn't support thread local allocation buffers");
duke@435:     return 0;
duke@435:   }
duke@435: 
duke@435:   // "obj" is the address of an object in a younger generation.  Allocate space
duke@435:   // for "obj" in the current (or some higher) generation, and copy "obj" into
duke@435:   // the newly allocated space, if possible, returning the result (or NULL if
duke@435:   // the allocation failed).
duke@435:   //
duke@435:   // The "obj_size" argument is just obj->size(), passed along so the caller can
duke@435:   // avoid repeating the virtual call to retrieve it.
duke@435:   //
duke@435:   // The "ref" argument, if non-NULL, is the address of some reference to "obj"
duke@435:   // (that is "*ref == obj"); some generations may use this information to, for
duke@435:   // example, influence placement decisions.
duke@435:   //
duke@435:   // The default implementation ignores "ref" and calls allocate().
duke@435:   virtual oop promote(oop obj, size_t obj_size, oop* ref);
duke@435: 
duke@435:   // Thread "thread_num" (0 <= i < ParalleGCThreads) wants to promote
duke@435:   // object "obj", whose original mark word was "m", and whose size is
duke@435:   // "word_sz".  If possible, allocate space for "obj", copy obj into it
duke@435:   // (taking care to copy "m" into the mark word when done, since the mark
duke@435:   // word of "obj" may have been overwritten with a forwarding pointer, and
duke@435:   // also taking care to copy the klass pointer *last*.  Returns the new
duke@435:   // object if successful, or else NULL.
duke@435:   virtual oop par_promote(int thread_num,
duke@435:                           oop obj, markOop m, size_t word_sz);
duke@435: 
duke@435:   // Undo, if possible, the most recent par_promote_alloc allocation by
duke@435:   // "thread_num" ("obj", of "word_sz").
duke@435:   virtual void par_promote_alloc_undo(int thread_num,
duke@435:                                       HeapWord* obj, size_t word_sz);
duke@435: 
duke@435:   // Informs the current generation that all par_promote_alloc's in the
duke@435:   // collection have been completed; any supporting data structures can be
duke@435:   // reset.  Default is to do nothing.
duke@435:   virtual void par_promote_alloc_done(int thread_num) {}
duke@435: 
duke@435:   // Informs the current generation that all oop_since_save_marks_iterates
duke@435:   // performed by "thread_num" in the current collection, if any, have been
duke@435:   // completed; any supporting data structures can be reset.  Default is to
duke@435:   // do nothing.
duke@435:   virtual void par_oop_since_save_marks_iterate_done(int thread_num) {}
duke@435: 
duke@435:   // This generation will collect all younger generations
duke@435:   // during a full collection.
duke@435:   virtual bool full_collects_younger_generations() const { return false; }
duke@435: 
duke@435:   // This generation does in-place marking, meaning that mark words
duke@435:   // are mutated during the marking phase and presumably reinitialized
duke@435:   // to a canonical value after the GC. This is currently used by the
duke@435:   // biased locking implementation to determine whether additional
duke@435:   // work is required during the GC prologue and epilogue.
duke@435:   virtual bool performs_in_place_marking() const { return true; }
duke@435: 
duke@435:   // Returns "true" iff collect() should subsequently be called on this
duke@435:   // this generation. See comment below.
duke@435:   // This is a generic implementation which can be overridden.
duke@435:   //
duke@435:   // Note: in the current (1.4) implementation, when genCollectedHeap's
duke@435:   // incremental_collection_will_fail flag is set, all allocations are
duke@435:   // slow path (the only fast-path place to allocate is DefNew, which
duke@435:   // will be full if the flag is set).
duke@435:   // Thus, older generations which collect younger generations should
duke@435:   // test this flag and collect if it is set.
duke@435:   virtual bool should_collect(bool   full,
duke@435:                               size_t word_size,
duke@435:                               bool   is_tlab) {
duke@435:     return (full || should_allocate(word_size, is_tlab));
duke@435:   }
duke@435: 
duke@435:   // Perform a garbage collection.
duke@435:   // If full is true attempt a full garbage collection of this generation.
duke@435:   // Otherwise, attempting to (at least) free enough space to support an
duke@435:   // allocation of the given "word_size".
duke@435:   virtual void collect(bool   full,
duke@435:                        bool   clear_all_soft_refs,
duke@435:                        size_t word_size,
duke@435:                        bool   is_tlab) = 0;
duke@435: 
duke@435:   // Perform a heap collection, attempting to create (at least) enough
duke@435:   // space to support an allocation of the given "word_size".  If
duke@435:   // successful, perform the allocation and return the resulting
duke@435:   // "oop" (initializing the allocated block). If the allocation is
duke@435:   // still unsuccessful, return "NULL".
duke@435:   virtual HeapWord* expand_and_allocate(size_t word_size,
duke@435:                                         bool is_tlab,
duke@435:                                         bool parallel = false) = 0;
duke@435: 
duke@435:   // Some generations may require some cleanup or preparation actions before
duke@435:   // allowing a collection.  The default is to do nothing.
duke@435:   virtual void gc_prologue(bool full) {};
duke@435: 
duke@435:   // Some generations may require some cleanup actions after a collection.
duke@435:   // The default is to do nothing.
duke@435:   virtual void gc_epilogue(bool full) {};
duke@435: 
duke@435:   // Some generations may need to be "fixed-up" after some allocation
duke@435:   // activity to make them parsable again. The default is to do nothing.
duke@435:   virtual void ensure_parsability() {};
duke@435: 
duke@435:   // Time (in ms) when we were last collected or now if a collection is
duke@435:   // in progress.
duke@435:   virtual jlong time_of_last_gc(jlong now) {
duke@435:     // XXX See note in genCollectedHeap::millis_since_last_gc()
duke@435:     NOT_PRODUCT(
duke@435:       if (now < _time_of_last_gc) {
duke@435:         warning("time warp: %d to %d", _time_of_last_gc, now);
duke@435:       }
duke@435:     )
duke@435:     return _time_of_last_gc;
duke@435:   }
duke@435: 
duke@435:   virtual void update_time_of_last_gc(jlong now)  {
duke@435:     _time_of_last_gc = now;
duke@435:   }
duke@435: 
duke@435:   // Generations may keep statistics about collection.  This
duke@435:   // method updates those statistics.  current_level is
duke@435:   // the level of the collection that has most recently
duke@435:   // occurred.  This allows the generation to decide what
duke@435:   // statistics are valid to collect.  For example, the
duke@435:   // generation can decide to gather the amount of promoted data
duke@435:   // if the collection of the younger generations has completed.
duke@435:   GCStats* gc_stats() const { return _gc_stats; }
duke@435:   virtual void update_gc_stats(int current_level, bool full) {}
duke@435: 
duke@435:   // Mark sweep support phase2
duke@435:   virtual void prepare_for_compaction(CompactPoint* cp);
duke@435:   // Mark sweep support phase3
duke@435:   virtual void pre_adjust_pointers() {ShouldNotReachHere();}
duke@435:   virtual void adjust_pointers();
duke@435:   // Mark sweep support phase4
duke@435:   virtual void compact();
duke@435:   virtual void post_compact() {ShouldNotReachHere();}
duke@435: 
duke@435:   // Support for CMS's rescan. In this general form we return a pointer
duke@435:   // to an abstract object that can be used, based on specific previously
duke@435:   // decided protocols, to exchange information between generations,
duke@435:   // information that may be useful for speeding up certain types of
duke@435:   // garbage collectors. A NULL value indicates to the client that
duke@435:   // no data recording is expected by the provider. The data-recorder is
duke@435:   // expected to be GC worker thread-local, with the worker index
duke@435:   // indicated by "thr_num".
duke@435:   virtual void* get_data_recorder(int thr_num) { return NULL; }
duke@435: 
duke@435:   // Some generations may require some cleanup actions before allowing
duke@435:   // a verification.
duke@435:   virtual void prepare_for_verify() {};
duke@435: 
duke@435:   // Accessing "marks".
duke@435: 
duke@435:   // This function gives a generation a chance to note a point between
duke@435:   // collections.  For example, a contiguous generation might note the
duke@435:   // beginning allocation point post-collection, which might allow some later
duke@435:   // operations to be optimized.
duke@435:   virtual void save_marks() {}
duke@435: 
duke@435:   // This function allows generations to initialize any "saved marks".  That
duke@435:   // is, should only be called when the generation is empty.
duke@435:   virtual void reset_saved_marks() {}
duke@435: 
duke@435:   // This function is "true" iff any no allocations have occurred in the
duke@435:   // generation since the last call to "save_marks".
duke@435:   virtual bool no_allocs_since_save_marks() = 0;
duke@435: 
duke@435:   // Apply "cl->apply" to (the addresses of) all reference fields in objects
duke@435:   // allocated in the current generation since the last call to "save_marks".
duke@435:   // If more objects are allocated in this generation as a result of applying
duke@435:   // the closure, iterates over reference fields in those objects as well.
duke@435:   // Calls "save_marks" at the end of the iteration.
duke@435:   // General signature...
duke@435:   virtual void oop_since_save_marks_iterate_v(OopsInGenClosure* cl) = 0;
duke@435:   // ...and specializations for de-virtualization.  (The general
duke@435:   // implemention of the _nv versions call the virtual version.
duke@435:   // Note that the _nv suffix is not really semantically necessary,
duke@435:   // but it avoids some not-so-useful warnings on Solaris.)
duke@435: #define Generation_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix)             \
duke@435:   virtual void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) {    \
duke@435:     oop_since_save_marks_iterate_v((OopsInGenClosure*)cl);                      \
duke@435:   }
duke@435:   SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(Generation_SINCE_SAVE_MARKS_DECL)
duke@435: 
duke@435: #undef Generation_SINCE_SAVE_MARKS_DECL
duke@435: 
duke@435:   // The "requestor" generation is performing some garbage collection
duke@435:   // action for which it would be useful to have scratch space.  If
duke@435:   // the target is not the requestor, no gc actions will be required
duke@435:   // of the target.  The requestor promises to allocate no more than
duke@435:   // "max_alloc_words" in the target generation (via promotion say,
duke@435:   // if the requestor is a young generation and the target is older).
duke@435:   // If the target generation can provide any scratch space, it adds
duke@435:   // it to "list", leaving "list" pointing to the head of the
duke@435:   // augmented list.  The default is to offer no space.
duke@435:   virtual void contribute_scratch(ScratchBlock*& list, Generation* requestor,
duke@435:                                   size_t max_alloc_words) {}
duke@435: 
duke@435:   // When an older generation has been collected, and perhaps resized,
duke@435:   // this method will be invoked on all younger generations (from older to
duke@435:   // younger), allowing them to resize themselves as appropriate.
duke@435:   virtual void compute_new_size() = 0;
duke@435: 
duke@435:   // Printing
duke@435:   virtual const char* name() const = 0;
duke@435:   virtual const char* short_name() const = 0;
duke@435: 
duke@435:   int level() const { return _level; }
duke@435: 
duke@435:   // Attributes
duke@435: 
duke@435:   // True iff the given generation may only be the youngest generation.
duke@435:   virtual bool must_be_youngest() const = 0;
duke@435:   // True iff the given generation may only be the oldest generation.
duke@435:   virtual bool must_be_oldest() const = 0;
duke@435: 
duke@435:   // Reference Processing accessor
duke@435:   ReferenceProcessor* const ref_processor() { return _ref_processor; }
duke@435: 
duke@435:   // Iteration.
duke@435: 
duke@435:   // Iterate over all the ref-containing fields of all objects in the
duke@435:   // generation, calling "cl.do_oop" on each.
duke@435:   virtual void oop_iterate(OopClosure* cl);
duke@435: 
duke@435:   // Same as above, restricted to the intersection of a memory region and
duke@435:   // the generation.
duke@435:   virtual void oop_iterate(MemRegion mr, OopClosure* cl);
duke@435: 
duke@435:   // Iterate over all objects in the generation, calling "cl.do_object" on
duke@435:   // each.
duke@435:   virtual void object_iterate(ObjectClosure* cl);
duke@435: 
duke@435:   // Iterate over all objects allocated in the generation since the last
duke@435:   // collection, calling "cl.do_object" on each.  The generation must have
duke@435:   // been initialized properly to support this function, or else this call
duke@435:   // will fail.
duke@435:   virtual void object_iterate_since_last_GC(ObjectClosure* cl) = 0;
duke@435: 
duke@435:   // Apply "cl->do_oop" to (the address of) all and only all the ref fields
duke@435:   // in the current generation that contain pointers to objects in younger
duke@435:   // generations. Objects allocated since the last "save_marks" call are
duke@435:   // excluded.
duke@435:   virtual void younger_refs_iterate(OopsInGenClosure* cl) = 0;
duke@435: 
duke@435:   // Inform a generation that it longer contains references to objects
duke@435:   // in any younger generation.    [e.g. Because younger gens are empty,
duke@435:   // clear the card table.]
duke@435:   virtual void clear_remembered_set() { }
duke@435: 
duke@435:   // Inform a generation that some of its objects have moved.  [e.g. The
duke@435:   // generation's spaces were compacted, invalidating the card table.]
duke@435:   virtual void invalidate_remembered_set() { }
duke@435: 
duke@435:   // Block abstraction.
duke@435: 
duke@435:   // Returns the address of the start of the "block" that contains the
duke@435:   // address "addr".  We say "blocks" instead of "object" since some heaps
duke@435:   // may not pack objects densely; a chunk may either be an object or a
duke@435:   // non-object.
duke@435:   virtual HeapWord* block_start(const void* addr) const;
duke@435: 
duke@435:   // Requires "addr" to be the start of a chunk, and returns its size.
duke@435:   // "addr + size" is required to be the start of a new chunk, or the end
duke@435:   // of the active area of the heap.
duke@435:   virtual size_t block_size(const HeapWord* addr) const ;
duke@435: 
duke@435:   // Requires "addr" to be the start of a block, and returns "TRUE" iff
duke@435:   // the block is an object.
duke@435:   virtual bool block_is_obj(const HeapWord* addr) const;
duke@435: 
duke@435: 
duke@435:   // PrintGC, PrintGCDetails support
duke@435:   void print_heap_change(size_t prev_used) const;
duke@435: 
duke@435:   // PrintHeapAtGC support
duke@435:   virtual void print() const;
duke@435:   virtual void print_on(outputStream* st) const;
duke@435: 
duke@435:   virtual void verify(bool allow_dirty) = 0;
duke@435: 
duke@435:   struct StatRecord {
duke@435:     int invocations;
duke@435:     elapsedTimer accumulated_time;
duke@435:     StatRecord() :
duke@435:       invocations(0),
duke@435:       accumulated_time(elapsedTimer()) {}
duke@435:   };
duke@435: private:
duke@435:   StatRecord _stat_record;
duke@435: public:
duke@435:   StatRecord* stat_record() { return &_stat_record; }
duke@435: 
duke@435:   virtual void print_summary_info();
duke@435:   virtual void print_summary_info_on(outputStream* st);
duke@435: 
duke@435:   // Performance Counter support
duke@435:   virtual void update_counters() = 0;
duke@435:   virtual CollectorCounters* counters() { return _gc_counters; }
duke@435: };
duke@435: 
duke@435: // Class CardGeneration is a generation that is covered by a card table,
duke@435: // and uses a card-size block-offset array to implement block_start.
duke@435: 
duke@435: // class BlockOffsetArray;
duke@435: // class BlockOffsetArrayContigSpace;
duke@435: class BlockOffsetSharedArray;
duke@435: 
duke@435: class CardGeneration: public Generation {
duke@435:   friend class VMStructs;
duke@435:  protected:
duke@435:   // This is shared with other generations.
duke@435:   GenRemSet* _rs;
duke@435:   // This is local to this generation.
duke@435:   BlockOffsetSharedArray* _bts;
duke@435: 
duke@435:   CardGeneration(ReservedSpace rs, size_t initial_byte_size, int level,
duke@435:                  GenRemSet* remset);
duke@435: 
duke@435:  public:
duke@435: 
duke@435:   virtual void clear_remembered_set();
duke@435: 
duke@435:   virtual void invalidate_remembered_set();
duke@435: 
duke@435:   virtual void prepare_for_verify();
duke@435: };
duke@435: 
duke@435: // OneContigSpaceCardGeneration models a heap of old objects contained in a single
duke@435: // contiguous space.
duke@435: //
duke@435: // Garbage collection is performed using mark-compact.
duke@435: 
duke@435: class OneContigSpaceCardGeneration: public CardGeneration {
duke@435:   friend class VMStructs;
duke@435:   // Abstractly, this is a subtype that gets access to protected fields.
duke@435:   friend class CompactingPermGen;
duke@435:   friend class VM_PopulateDumpSharedSpace;
duke@435: 
duke@435:  protected:
duke@435:   size_t     _min_heap_delta_bytes;   // Minimum amount to expand.
duke@435:   ContiguousSpace*  _the_space;       // actual space holding objects
duke@435:   WaterMark  _last_gc;                // watermark between objects allocated before
duke@435:                                       // and after last GC.
duke@435: 
duke@435:   // Grow generation with specified size (returns false if unable to grow)
duke@435:   bool grow_by(size_t bytes);
duke@435:   // Grow generation to reserved size.
duke@435:   bool grow_to_reserved();
duke@435:   // Shrink generation with specified size (returns false if unable to shrink)
duke@435:   void shrink_by(size_t bytes);
duke@435: 
duke@435:   // Allocation failure
duke@435:   void expand(size_t bytes, size_t expand_bytes);
duke@435:   void shrink(size_t bytes);
duke@435: 
duke@435:   // Accessing spaces
duke@435:   ContiguousSpace* the_space() const { return _the_space; }
duke@435: 
duke@435:  public:
duke@435:   OneContigSpaceCardGeneration(ReservedSpace rs, size_t initial_byte_size,
duke@435:                                size_t min_heap_delta_bytes,
duke@435:                                int level, GenRemSet* remset,
duke@435:                                ContiguousSpace* space) :
duke@435:     CardGeneration(rs, initial_byte_size, level, remset),
duke@435:     _the_space(space), _min_heap_delta_bytes(min_heap_delta_bytes)
duke@435:   {}
duke@435: 
duke@435:   inline bool is_in(const void* p) const;
duke@435: 
duke@435:   // Space enquiries
duke@435:   size_t capacity() const;
duke@435:   size_t used() const;
duke@435:   size_t free() const;
duke@435: 
duke@435:   MemRegion used_region() const;
duke@435: 
duke@435:   size_t unsafe_max_alloc_nogc() const;
duke@435:   size_t contiguous_available() const;
duke@435: 
duke@435:   // Iteration
duke@435:   void object_iterate(ObjectClosure* blk);
duke@435:   void space_iterate(SpaceClosure* blk, bool usedOnly = false);
duke@435:   void object_iterate_since_last_GC(ObjectClosure* cl);
duke@435: 
duke@435:   void younger_refs_iterate(OopsInGenClosure* blk);
duke@435: 
duke@435:   inline CompactibleSpace* first_compaction_space() const;
duke@435: 
duke@435:   virtual inline HeapWord* allocate(size_t word_size, bool is_tlab);
duke@435:   virtual inline HeapWord* par_allocate(size_t word_size, bool is_tlab);
duke@435: 
duke@435:   // Accessing marks
duke@435:   inline WaterMark top_mark();
duke@435:   inline WaterMark bottom_mark();
duke@435: 
duke@435: #define OneContig_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix)      \
duke@435:   void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl);
duke@435:   OneContig_SINCE_SAVE_MARKS_DECL(OopsInGenClosure,_v)
duke@435:   SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(OneContig_SINCE_SAVE_MARKS_DECL)
duke@435: 
duke@435:   void save_marks();
duke@435:   void reset_saved_marks();
duke@435:   bool no_allocs_since_save_marks();
duke@435: 
duke@435:   inline size_t block_size(const HeapWord* addr) const;
duke@435: 
duke@435:   inline bool block_is_obj(const HeapWord* addr) const;
duke@435: 
duke@435:   virtual void collect(bool full,
duke@435:                        bool clear_all_soft_refs,
duke@435:                        size_t size,
duke@435:                        bool is_tlab);
duke@435:   HeapWord* expand_and_allocate(size_t size,
duke@435:                                 bool is_tlab,
duke@435:                                 bool parallel = false);
duke@435: 
duke@435:   virtual void prepare_for_verify();
duke@435: 
duke@435:   virtual void gc_epilogue(bool full);
duke@435: 
duke@435:   virtual void verify(bool allow_dirty);
duke@435:   virtual void print_on(outputStream* st) const;
duke@435: };